1. Field of Endeavor
The present invention relates to accelerometers and more particularly to a fiber optic micro accelerometer.
2. State of Technology
U.S. Pat. No. 4,595,830 for a multimode optical fiber accelerometer by Donald McMahon issued Jun. 17, 1986 provides the following information, “Accelerometers of the prior art include devices comprising a proof mass affixed to the end of an elastic beam. The elastic beam, owing to the inertia of the affixed proof mass, bends upon acceleration, providing a measurement thereof. Alternatively, upon acceleration, a feedback loop generates a countervailing force which maintains the original position of the proof mass. The acceleration is derived from a measurement of the necessary compensating force. Sensors in these prior art devices for detecting relevant changes from which the acceleration may be calculated, comprise mechanical or electromagnetic means, or combinations thereof. Thus, there is a need for an efficacious accelerometer entailing optical, in particular, optical fiber sensors.”
U.S. Pat. No. 5,276,322 for a fiber optic accelerometer by Edward Carome issued Apr. 1, 1994 provides the following information, “Heretofore, the acceleration and vibration sensors have been primarily of electromechanical nature. One prior art acceleration sensor uses a mercury switch which is configured such that the selected acceleration moves the mercury to a position in which it closes an electrical connection between leads. Prior art vibration sensors utilize electrical conductors moving with respect to magnetic fields or piezoelectric elements that produce electric signals proportional to acceleration. Fiber optic accelerometers of numerous designs are available. The fiber optic systems have numerous advantages over mechanical and electromechanical accelerometers, such as their increased sensitivity and immunity to electrical interference. However, the fiber optic accelerometers tend to be relatively expensive. Moreover, the fiber optic accelerometers are not as amenable to automated manufacture as the prior art electromechanical and electrical acceleration sensors.”
U.S. Pat. No. 6,175,108 for an accelerometer featuring fiber optic bragg grating sensor for providing multiplexed multi-axis acceleration sensing by Richard Jones, et al. issued Jan. 16, 2001 provides the following information, “Accelerometers are known in the prior art that use an optical fiber. Such accelerometers measure acceleration by sensing optical fiber surface strain, by sending optical fiber displacement or microbending, by sensing optical signal intensity, and by sensing optical signal phase shifts. One disadvantage of the prior art accelerometers is that they are all complicated point sensors that do not allow multiplexing. Instead, a separate prior art accelerometer is needed to sense each respective axis.”